1. Field of the Invention
The present invention relates to a rotating polygon mirror driving apparatus used for laser scanning in a laser beam printer (referred to as "LBP" hereinafter).
2. Description of the Prior Art
Recently, there have been increasing demands for decreasing the size, thickness and cost of a rotating polygon mirror driving apparatus as LBP is have been popularized. In this situation, attempts are made to decrease the thickness and cost by fixing an aluminum or brass sleeve to, for example, an iron substrate, in place of a conventional bracket made of an aluminum die casting or the like. However, it is necessary to prevent occurrence of rational fluctuations (referred to as "jitter" hereinafter), noise or a tilt of a rotating polygon mirror to maintain high-precision performance. The measure of using a fluid bearing as a bearing is made to attempt to increase the precision.
Examples of conventional rotating polygon mirror driving apparatuses are described below with reference to FIGS. 3 and 4.